Is the Udhiyah obligatory for a Muslim every year, or is it sufficient once in a lifetime if one has the means?

The Udhiyah (sacrifice) is a confirmed Sunnah every year, and one year's sacrifice does not suffice for the years thereafter, because it is repeated with the repetition of its time, just like prayer. The Messenger of Allah (peace be upon him) said: "O people, for every household, there is an Udhiyah every year." No scholar has ever said that a single Udhiyah is sufficient for a person for all years.